A method for total static pressure compensation correction based on helicopter flight status

Abstract

This application provides a method for total static pressure compensation correction based on helicopter flight status, belonging to the field of helicopter control technology. Specifically, it includes: comparing and analyzing actual flight data with collected data to obtain a table of total static pressure correction values ​​for different airspeed descent rates; collecting the indicated total pressure and indicated static pressure of the current product and calculating the indicated airspeed; calculating the total pressure correction and static pressure correction values ​​for the current cycle based on the indicated airspeed calculated in the current cycle and the climb / deceleration calculated in the previous cycle, referring to the table; obtaining the true static pressure and true total pressure based on the correction values; calculating the true indicated airspeed based on the true static pressure and true total pressure; and obtaining the climb / deceleration for the current cycle based on the climb / deceleration calculation formula using the true static pressure. This application's solution can obtain accurate data sources, avoid erroneous airspeed corrections, more closely approximate true airspeed, benefit flight control, and improve flight quality.

Description

Technical Field

[0001] This application relates to the field of helicopter control technology, and in particular to a method for total static pressure compensation correction based on helicopter flight status. Background Technology

[0002] The most significant characteristic of distributed air data systems compared to triaxial air data systems is that the pitot tube measurement angle is fixed, limiting the measurement to a certain angle of attack directly in front of the helicopter's nose. Therefore, when the incoming airflow angle of attack exceeds the pitot tube's insensitive range, the total pressure measurement loss increases exponentially. Furthermore, due to the helicopter's nose profile, the static pressure measurement in the distributed air data system is in a negative pressure zone, with the measured static pressure being lower than the actual static pressure, ultimately leading to abnormal airspeed signal calculations. A simple solution to airspeed anomalies is to directly correct the airspeed to smoothly navigate the abnormal range. This method improves the output airspeed quality but does not fundamentally address the root cause of the anomalies. With the increasing number of different helicopters and flight conditions, it is essential to fundamentally resolve airspeed anomalies by correcting the original measured total static pressure. Summary of the Invention

[0003] In view of this, this application provides a method for total static pressure compensation correction based on helicopter flight status, which at least partially solves the problems existing in the prior art: When a helicopter climbs or descends while flying forward, if the angle between the sum of the velocity vectors exceeds the pitot tube measurement angle, the total pressure loss increases in an indicative manner as the excess angle increases. Simultaneously, different forward flight speeds cause changes in the negative pressure zone near the air data system, leading to inaccurate static pressure measurements. Ultimately, the calculated indicated airspeed differs from the aircraft's actual airspeed, a phenomenon more pronounced at low speeds. Inaccurate airspeed can cause abnormal judgments of aircraft attitude by the flight control system, affecting flight control and flight experience.

[0004] This application provides a method for total static pressure compensation correction based on helicopter flight status, the method comprising:

[0005] Based on the comparative analysis of actual flight data and collected data, a static pressure correction table and a total pressure correction table for the atmospheric engine under different airspeed descent rates were obtained. One array of the static pressure correction table corresponds to a static pressure correction for a climb rate and an indicated airspeed, and one array of the total pressure correction table corresponds to a total pressure correction for a climb rate and an indicated airspeed.

[0006] Collect the indicated total pressure and indicated static pressure of the current product;

[0007] Based on the indicated total pressure and the indicated static pressure, the indicated airspeed is calculated using the indicated airspeed calculation formula.

[0008] Based on the indicated airspeed calculated in this cycle and the acceleration / deceleration calculated in the previous cycle, the static pressure correction for this cycle is calculated using the static pressure correction table, and the total pressure correction for this cycle is calculated using the total pressure correction table.

[0009] The true static pressure is obtained based on the indicated static pressure and the static pressure correction amount for this cycle; the true total pressure is obtained based on the indicated total pressure and the total pressure correction amount for this cycle.

[0010] The actual indicated airspeed is calculated based on the actual static pressure and the actual total pressure, using the indicated airspeed calculation formula.

[0011] Based on the actual static pressure, the lifting speed for this cycle is obtained using the lifting speed calculation formula.

[0012] According to a specific implementation of an embodiment of this application, the indicated total pressure and indicated static pressure of the current product are collected, including:

[0013] The total pressure and static pressure are collected by the total pressure sensor and static pressure sensor inside the product, respectively.

[0014] According to a specific implementation of an embodiment of this application, the indicated airspeed calculation formula is as follows:

[0015] When M≤1

[0016] When M > 1

[0017] Where M is the Mach number, q c Dynamic pressure is the difference between the indicated total pressure and the indicated static pressure, in kPa; V i Airspeed is indicated by the unit: km / h; P n The standard atmospheric pressure at sea level is 101.325 kPa, in kPa; k is the adiabatic index, and c is the thermal index. n The speed of sound at sea level is expressed in m / s.

[0018] According to a specific implementation of an embodiment of this application, the step of calculating the static pressure correction for the current cycle based on the indicated airspeed calculated in the current cycle and the acceleration / deceleration calculated in the previous cycle, using the static pressure correction lookup table, and calculating the total pressure correction for the current cycle using the total pressure correction lookup table, includes:

[0019] The indicated airspeed calculated in the current cycle and the acceleration / deceleration calculated in the previous cycle are used as the data elements to be queried.

[0020] When the data element to be looked up falls within the data range of the static pressure correction table and the total pressure correction table, the binary lookup table method is used to find the position of the data element in the array and obtain the static pressure correction and the total pressure correction for the current period.

[0021] According to a specific implementation of an embodiment of this application, the step of using a binary lookup table method to find the position of the data element to be searched in the array and obtaining the static pressure correction amount and the total pressure correction amount for the current cycle includes:

[0022] Based on the data element to be checked, in the static pressure correction table or the total pressure correction table, the indicated airspeed calculated in the current cycle is interpolated between two adjacent indicated airspeeds that can include the indicated airspeed calculated in the current cycle, and the acceleration / deceleration calculated in the previous cycle is interpolated between two adjacent acceleration / decelerations that can include the acceleration / deceleration calculated in the previous cycle.

[0023] Based on the pressure correction calculation formula, the static pressure correction and the total pressure correction for this cycle are calculated separately. The pressure correction calculation formula is as follows:

[0024] de lta1=(Pb1-Pa1)*(vi-via) / (vib-via)+Pa1

[0025] de lta2=(Pb2-Pa2)*(vi-via) / (vib-via)+Pa2

[0026] de lta=(de lta2-de lta1)*(hr-hra) / (hrb-hra)+de lta1

[0027] Where de lta is the pressure correction value, de lta1 and de lta2 are the interpolation ranges of the current deceleration rate under the current indicated airspeed vi, vi a and vib are two adjacent indicated airspeeds that can include the indicated airspeed calculated in the current cycle, hr and hb are two adjacent deceleration rates that can include the deceleration rate calculated in the previous cycle, Pa1, Pb1, Pa2, and Pb2 are the pressure correction values ​​corresponding to the positions (via, hra), (vi b, hra), (via, hrb), and (vib, hrb), respectively, vi is the indicated airspeed calculated in the current cycle, and hr is the deceleration rate calculated in the previous cycle.

[0028] According to a specific implementation of an embodiment of this application, the formula for calculating the acceleration and deceleration speed is as follows:

[0029] Hrate = dhp * (Ps0avg - Ps1avg) / (static pressure sampling time * half the length of the static pressure filter array);

[0030] Where: Hrate is the rate of ascent and dhp is the reciprocal of the atmospheric pressure gradient; Ps0avg is the average value of the first half of the static pressure filter array after removing the maximum and minimum values; Ps1avg is the average value of the second half of the static pressure filter array after removing the maximum and minimum values.

[0031] Beneficial effects:

[0032] The method for total static pressure compensation correction based on helicopter flight status in this embodiment establishes a correspondence between the measured total static pressure and the actual total static pressure of the aircraft at different airspeeds and different climb / descendancy rates using an atmospheric data system. When the aircraft is in a certain state, the method compensates for the loss of measured pressure to obtain the actual pressure and other atmospheric parameters of the aircraft. By introducing airspeed and climb / descendancy rates, which reflect the helicopter's state, the method abandons the approach of directly compensating for airspeed and directly compensates for abnormal pressure at the source. This provides an accurate data source, avoids erroneous airspeed corrections, and more closely approximates the true airspeed, which is beneficial for flight control and improves flight quality. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the airspeed line calculated by a method for total static pressure compensation correction based on helicopter flight status according to an embodiment of the present invention. Detailed Implementation

[0035] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0036] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0038] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0039] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0040] This application provides a method for total static pressure compensation correction based on helicopter flight status, as described below. Figure 1 Provide a detailed description.

[0041] This application provides a method for total static pressure compensation correction based on helicopter flight status, the method comprising:

[0042] Step 1: Based on the actual flight data and the collected data, a comparative analysis is performed to obtain a static pressure correction table and a total pressure correction table for the atmospheric engine at different airspeed descent rates. One array of the static pressure correction table corresponds to a static pressure correction for a climb rate and an indicated airspeed, and one array of the total pressure correction table corresponds to a total pressure correction for a climb rate and an indicated airspeed.

[0043] Step 2: Collect the indicated total pressure and indicated static pressure of the current product;

[0044] Step 3: Calculate the indicated airspeed based on the indicated total pressure and the indicated static pressure, using the indicated airspeed calculation formula.

[0045] Step 4: Based on the indicated airspeed calculated in this cycle and the acceleration / deceleration calculated in the previous cycle, calculate the static pressure correction for this cycle using the static pressure correction table, and calculate the total pressure correction for this cycle using the total pressure correction table.

[0046] Step 5: Obtain the true static pressure based on the indicated static pressure and the static pressure correction amount for this cycle; obtain the true total pressure based on the indicated total pressure and the total pressure correction amount for this cycle.

[0047] Step 6: Calculate the actual indicated airspeed based on the actual static pressure and the actual total pressure, using the indicated airspeed calculation formula.

[0048] Step 7: Based on the actual static pressure, obtain the lifting speed for this cycle using the lifting speed calculation formula.

[0049] As the forward speed increases, the influence on static pressure gradually decreases; under the condition of a constant forward speed, the larger the absolute value of the climb and fall speed, the larger the local angle of attack, and the larger the error in measuring total pressure. When the angle of attack exceeds the critical angle, the total pressure error increases exponentially.

[0050] This embodiment establishes a correspondence (reference table) between the total static pressure measured by the atmospheric data system and the actual total static pressure of the aircraft at different airspeeds and different climb / descendancy rates. When the aircraft is in a certain state, the corresponding compensation for the loss of measured pressure is obtained to obtain the actual pressure and other atmospheric parameters of the aircraft. Therefore, by introducing airspeed and climb / descendancy rates, which can reflect the helicopter's state, to compensate for the loss of total static pressure and improve the accuracy of airspeed, it has important practical significance for improving flight quality.

[0051] Furthermore, the indicated total pressure and indicated static pressure of the current product are collected, including:

[0052] The total pressure and static pressure are collected by the total pressure sensor and static pressure sensor inside the product, respectively.

[0053] Furthermore, the calculation formulas for indicated airspeed differ between subsonic and supersonic conditions. The indicated airspeed is calculated in segments using the formula, and the indicated airspeed calculation formula is as follows:

[0054] When M≤1

[0055] When M > 1

[0056] Where M is the Mach number, q c Dynamic pressure is the difference between the indicated total pressure and the indicated static pressure, in kPa; V i Airspeed is indicated by the unit: km / h; P n The standard atmospheric pressure at sea level is 101.325 kPa, unit: kPa; k is the adiabatic index, with a value of 1.4; c n The speed of sound at sea level is expressed in m / s, and its value is 340.294 m / s.

[0057] Furthermore, the indicated airspeed calculated based on the current cycle and the acceleration / deceleration calculated in the previous cycle, the static pressure correction for the current cycle is calculated using the static pressure correction lookup table, and the total pressure correction for the current cycle is calculated using the total pressure correction lookup table, including:

[0058] The indicated airspeed calculated in the current cycle and the acceleration / deceleration calculated in the previous cycle are used as the data elements to be queried.

[0059] When the data element to be looked up falls within the data range of the static pressure correction table and the total pressure correction table, the binary lookup table method is used to find the position of the data element in the array and obtain the static pressure correction and the total pressure correction for the current period.

[0060] In practice, the static pressure correction tables include Table 1 (for different airspeed descent rates) for the left engine and Table 3 (for different airspeed descent rates) for the right engine. The total pressure correction tables include Table 2 (for different airspeed descent rates) for the left engine and Table 4 (for different airspeed descent rates) for the right engine. In the tables, ΔPsL represents the static pressure correction for the left engine, PtL represents the total pressure correction for the left engine, PsR represents the static pressure correction for the right engine, and PtR represents the total pressure correction for the right engine. The pressure correction data in the tables are derived by comparing and analyzing actual flight data with collected data, and by adjusting for experience.

[0061] Table 1. Correction for left atmospheric turbine static pressure at different airspeed descent rates

[0062]

[0063]

[0064] Table 2 Correction for Total Pressure of Left Atmosphere Engine at Different Airspeed Descent Rates

[0065]

[0066] Table 3 Correction for right atmospheric engine static pressure at different airspeed descent rates

[0067]

[0068] Table 4 Correction for Total Right Atmosphere Pressure at Different Airspeed Descent Rates

[0069]

[0070]

[0071] Furthermore, the step of using a binary lookup table method to find the position of the data element to be searched in the array, and obtaining the static pressure correction amount and the total pressure correction amount for the current period, includes:

[0072] Based on the data element to be checked, in the static pressure correction table or the total pressure correction table, the indicated airspeed calculated in the current cycle is interpolated between two adjacent indicated airspeeds that can include the indicated airspeed calculated in the current cycle, and the acceleration / deceleration calculated in the previous cycle is interpolated between two adjacent acceleration / decelerations that can include the acceleration / deceleration calculated in the previous cycle.

[0073] Based on the pressure correction calculation formula, the static pressure correction and the total pressure correction for this cycle are calculated separately. The pressure correction calculation formula is as follows:

[0074] de l ta1=(Pb1-Pa1)*(vi-vi a) / (vi b-vi a)+Pa1

[0075] de l ta2=(Pb2-Pa2)*(vi-vi a) / (vi b-vi a)+Pa2

[0076] de l ta=(de l ta2-de l ta1)*(hr-hra) / (hrb-hra)+de l ta1

[0077] Where de l ta is the pressure correction value, de l ta1 and de l ta2 are the interpolation ranges of the current deceleration rate under the current indicated airspeed vi, vi a and vi b are two adjacent indicated airspeeds that can include the indicated airspeed calculated in the current cycle, hr and hb are two adjacent deceleration rates that can include the deceleration rate calculated in the previous cycle, Pa1, Pb1, Pa2, Pb2 are the pressure correction values ​​corresponding to the positions (vi a, hra), (vi b, hra), (vi a, hrb), and (vib, hrb), respectively, vi is the indicated airspeed calculated in the current cycle, and hr is the deceleration rate calculated in the previous cycle.

[0078] In practice, based on the indicated airspeed calculated in this cycle and the acceleration / deceleration calculated in the previous cycle, the total pressure correction and static pressure correction for this cycle are calculated by referring to Tables 1 to 4 respectively using the pressure correction calculation formula. The actual total pressure and actual static pressure are also calculated. The acceleration / deceleration is set to 0 for the first calculation.

[0079] The binary lookup table method specifically includes the following:

[0080] The result is 0 when the element to be queried is less than the first element of the array.

[0081] If the element to be queried is greater than the last element of the array, return the result (array length - 2);

[0082] If the first two conditions are not met, the binary lookup table method is used to find the left-hand position of the data element to be searched in the array and the corresponding result is returned. The formulas for calculating the true total pressure and the true static pressure are as follows:

[0083] Actual total pressure = Indicated total pressure + Total pressure correction;

[0084] Actual static pressure = indicated static pressure + static pressure correction.

[0085] According to a specific implementation of an embodiment of this application, the formula for calculating the acceleration and deceleration speed is as follows:

[0086] Hrate = dhp * (Ps0avg - Ps1avg) / (static pressure sampling time * half the length of the static pressure filter array);

[0087] Where: Hrate is the rate of ascent and descent, dhp is the reciprocal of the atmospheric pressure gradient; Ps0avg is the average value of the first half of the static pressure filter array after removing the maximum and minimum values; Ps1avg is the average value of the second half of the static pressure filter array after removing the maximum and minimum values. The length of the filter array is empirically set to 40.

[0088] The airspeed line calculated based on the method of this application is as follows: Figure 1 As shown.

[0089] The embodiment provided by this invention, which compensates for total static pressure based on aircraft status, for airspeed correction. Compared with existing airspeed correction methods, this method abandons the idea of ​​directly compensating for airspeed and instead directly compensates for abnormal pressure at the source. This provides an accurate data source, avoids erroneous airspeed correction, and is closer to the true airspeed, which is beneficial for flight control and improves flight quality.

[0090] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for total pressure compensation correction based on a helicopter flight state, characterized in that, The method comprises: Comparative analysis is performed on the actual flight data and the collected data to obtain an atmospheric machine static pressure correction table and an atmospheric machine total pressure correction table at different air speed descent rates, one array of the static pressure correction table corresponding to a static pressure correction amount of one air speed and one descent rate, and one array of the total pressure correction table corresponding to a total pressure correction amount of one air speed and one descent rate; Collecting an indicated total pressure and an indicated static pressure of a current product; Calculating an indicated air speed based on an indicated air speed calculation formula according to the indicated total pressure and the indicated static pressure; Based on the indicated air speed calculated in the current period and the descent rate calculated in the last period, calculating a current period static pressure correction amount through the static pressure correction table and calculating a current period total pressure correction amount through the total pressure correction table; Based on the indicated static pressure and the current period static pressure correction amount, obtaining a real static pressure; and based on the indicated total pressure and the current period total pressure correction amount, obtaining a real total pressure; Based on the indicated air speed calculation formula, calculating a real indicated air speed according to the real static pressure and the real total pressure; Based on a descent rate solving formula, obtaining a current period descent rate according to the real static pressure.

2. The method of total pressure correction based on the flight state of a helicopter according to claim 1, characterized in that, Collecting an indicated total pressure and an indicated static pressure of a current product comprises: Collecting the indicated total pressure and the indicated static pressure through a total pressure sensor and a static pressure sensor inside the product.

3. The method of correcting for total pressure error based on the flight condition of a helicopter according to claim 1, wherein, The indicated air speed calculation formula is: When M < 1, When M > 1, wherein M is the Mach number, q c is the dynamic pressure, which is the difference between the total pressure and the static pressure, in kPa; V i is the indicated airspeed, in km / h; P n is the sea level standard atmospheric pressure 101.325 kPa, in kPa; k is the adiabatic index, c n is the sea level standard sonic speed, in m / s.

4. The method of correcting for total pressure error based on a helicopter flight condition according to claim 1, wherein, Based on the indicated air speed calculated in the current period and the descent rate calculated in the last period, calculating a current period static pressure correction amount through the static pressure correction table and calculating a current period total pressure correction amount through the total pressure correction table comprises: Taking the indicated air speed calculated in the current period and the descent rate calculated in the last period as a data element to be searched; When the data element to be searched is within the data range in the static pressure correction table and the total pressure correction table, using a dichotomy search table method to search for the position of the data element to be searched in the array to obtain the current period static pressure correction amount and the current period total pressure correction amount.

5. The method of total pressure correction based on the flight state of a helicopter according to claim 4, characterized in that, The dichotomy search table method comprises: According to the data element to be searched, interpolating the indicated air speed calculated in the current period between two adjacent indicated air speeds containing the indicated air speed calculated in the current period and interpolating the descent rate calculated in the last period between two adjacent descent rates containing the descent rate calculated in the last period in the static pressure correction table or the total pressure correction table; According to a pressure correction amount calculation formula, calculating the current period static pressure correction amount and the current period total pressure correction amount, the pressure correction amount calculation formula being: delta1 = (Pb1 - Pa1) * (vi - via) / (vib - via) + Pa1 delta2 = (Pb2 - Pa2) * (vi - via) / (vib - via) + Pa2 delta = (delta2 - delta1) * (hr - hra) / (hrb - hra) + delta1 Wherein, delta is the pressure correction value, delta1 and delta2 are the interpolation range of the current lift-drag speed at the current indicated air speed vi, via and vib are respectively the adjacent two indicated air speeds containing the indicated air speed calculated in the current period, hr and hb are respectively the adjacent two lift-drag speeds containing the lift-drag speed calculated in the last period, Pa1, Pb1, Pa2, Pb2 are respectively the pressure correction values of the positions (via, hra), (vib, hra), (via, hrb), (vib, hrb), vi is the indicated air speed calculated in the current period, and hr is the lift-drag speed calculated in the last period.

6. The method of correcting for total pressure error based on a helicopter flight condition according to claim 1, wherein, The lift-drag speed calculation formula is: Hrate = dhp * (Ps0avg - Ps1 avg) / (static pressure sampling time * half of the length of the static pressure filtering array); Wherein, Hrate is the lift-drag speed, dhp is the reciprocal of the atmospheric pressure gradient, Ps0avg is the average value of the first half of the static pressure filtering array after removing the maximum and minimum values, and Ps1 avg is the average value of the second half of the static pressure filtering array after removing the maximum and minimum values.

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